Mechanical devices often require an assembly that allows linear motion with essentially no static friction involved. In many instances, such functionality has been provided via flexures, which consist primarily of two or more semi-rigid elastic members attaching a stable base to a plate or other object that is to be allowed to move in some specified direction. For example, FIG. 1 shows a one-dimensional flexure assembly 100, having a base plate 110, to which four flexures 120 are attached using screws 130. At the opposite end of each flexure 120 is attached the moving object, which in this case is a moving plate 50. Each flexure 120 is thin enough to allow translational movement of moving plate 50 perpendicular to flexures 120, as indicated by the arrow displayed in FIG. 1. Additionally, the object to be moved is not limited to a plate such as the moving plate 50, but may be something rigidly attached to the moving plate 50, or may replace the moving plate 50 entirely.
At times, two-dimensional movement of the object may be desired, depending on the particular application involved. In such cases, a two-dimensional flexure assembly, such as an assembly 200 shown in FIG. 2, is employed to allow such motion. Again, a base plate 110 is typically used, to which the ends of four flexures 120 are attached. At the opposite end of each of the flexures 120 is attached an intermediate plate 210, which moves one-dimensionally as allowed by the four flexures 120 attached to the base plate 110. A second set of four flexures 120 is then attached at one end to intermediate plate 210, and oriented perpendicular to the first four flexures 120 attached to base plate 110 so that the movement allowed by the second four flexures 120 is essentially perpendicular to that allowed by the first four flexures 120. The ends of the second four flexures 120 opposite those attached to intermediate plate 210 are connected to a moving plate 50, thus allowing the moving plate 50 to translate two-dimensionally in any direction parallel to base plate 110, as indicated by the arrows shown in FIG. 2.
Unfortunately, two-dimensional flexure assemblies such as assembly 200 shown in FIG. 2 require multiple components, which in this case are two plates, eight flexures, and a multitude of screws, bolts, rivets, or equivalent connectors. Such a high part count typically results in increased cost, prolonged assembly time, and a possible decrease in assembly reliability.
Therefore, from the foregoing, a new two-dimensional flexure and flexure apparatus comprised of fewer components, thus enhancing reliability while diminishing part cost and assembly time, would be advantageous.
Embodiments of the present invention, to be discussed in detail below, allow for a two-axis flexure and flexure apparatus, each of which is made of a single contiguous piece of semi-rigid material. The flexure has a first and second flexure section, with the second flexure section being oriented so that the direction of translational motion allowed by that second flexure section is essentially perpendicular to that allowed by the first flexure section. Such flexures may be used in various multi-piece two-dimensional flexure assemblies.
A single-piece flexure apparatus, according to an embodiment of the invention, has a base section, and two or more legs extending substantially perpendicularly from the base section. Each of the legs has a first and second flexure section, with the first flexure section being positioned between the base section and the second flexure section. The second flexure section of each leg is oriented so that the direction of translational motion allowed by that second flexure section is essentially perpendicular to that allowed by the first flexure section. An object coupled to the second flexure section of each leg would then be allowed to move in two dimensions perpendicular to the legs.
Other aspects and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.